1. Field of the Invention
The present invention generally relates to information processing apparatuses, power control methods and recording media, and more particularly to an information processing apparatus which drives a plurality of processing units according to different types of files, a power control method therefor and a recording medium used therewith.
In recent years, information processing apparatuses have become small sized and portable because they can operate using batteries. Maximum reduction of dissipation power is needed for these apparatuses. On the other hand, multimedia devices have progressed, such that data which is processed in the information processing apparatuses now consist of a plurality of types of data such as moving pictures, sound and still pictures. It is necessary to activate a graphics board to display the moving pictures and still pictures and to activate a sound board to play back the sound data. However, only the sound board needs to be activated when the sound data is played back, but the moving pictures and still pictures are not displayed. In this case, if both the sound board and the graphics board are activated together, the power efficiency degrades because power which is supplied to the graphics board is wasted. Accordingly, it is desired to raise the power efficiency.
2. Description of the Related Art
Conventionally, personal computers use power save functions which become active if an access to the personal computers does not occur or each of processing units spontaneously moves into a suspend mode. Japanese Laid-Open Patent Application No. 57-104992, Japanese Laid-Open Patent Application No. 62-34218, Japanese Laid-Open Patent Application No. 4-364266, Japanese Laid-Open Patent Application No. 8-307783 and Japanese Laid-Open Patent Application No. 9-163043 disclose examples of methods to achieve a high power efficiency for electrical apparatuses.
Japanese Laid-Open Patent Application No. 57-104992 discloses a power save control method. In the method, a first mode or a second mode is detected. When the second mode is detected, power which is supplied in the first mode is shut down. Therefore, the first mode becomes inactive when the second mode is active.
Japanese Laid-Open Patent Application No. 62-34218 discloses an electrical apparatus of which operators can decide whether to execute a power save operation.
Japanese Laid-Open Patent Application No. 4-364266 discloses a power save apparatus for a sound circuit to shut down the sound circuit according to a result of detection of whether a CD is a CD-ROM or a musical CD based on TOC (Table of Contents) information.
Japanese Laid-Open Patent Application No. 8-307783 discloses a television apparatus which is equipped with a CD player. The television apparatus detects whether a CD is in place in the CD player. If the CD is in place in the CD player, the television apparatus detects a type of the CD. Then, the television apparatus controls the CD player according to the presence of the CD in it and drives necessary circuits according to the type of the CD.
Japanese Laid-Open Patent Application No. 9-163043 discloses a copy system, to which sub-controllers for expansion may or may not be connected, which copy system enables an optimum power save control. However, the copy system does not execute the power save control if the sub-controllers for expansion are not connected.
The method disclosed in Japanese Laid-Open Patent Application No. 57-104992 only executes the power save control according to the mode. Therefore, the method does not achieve a precise power save control according to a type of data or for each of the processing units.
In the method disclosed in Japanese Laid-Open Patent Application No. 62-34218, each of the processing units which is not used must be manually shut down. As users don't usually shut down the processing units, power is not saved.
The apparatus disclosed in Japanese Laid-Open Patent Application No. 4-364266 executes a power save control according to the TOC information of each medium when a CD-ROM is inserted and its TOC information is read. Therefore, it does not achieve the precise power save control.
The apparatus disclosed in Japanese Laid-Open Patent Application No. 8-307783 controls circuits according to whether a CD is inserted in it and the type of CD when the CD is inserted. It does not execute the precise power save control according to information recorded on the CD or for each processing unit which is driven.
The copy system disclosed in Japanese Laid-Open Patent Application No. 9-163043 only executes the power save control when the sub-controllers for expansion are connected. Therefore, it does not achieve the precise power save control according to the type of data or for each of the processing units.